Pseudo-differential class C amplifiers have a common mode current draw that varies depending on the input swing, which may not be controllable. A common mode feedback loop is, therefore, usually employed, even in a resistively loaded wide bandwidth amplifier, to stabilize the output common-mode under the varying class C current. This common-mode feedback should reduce degradation of differential bandwidth and maintain a first settling time for rapid duty cycling. However, no such feedback circuit has been developed. Thus, there is a need for an improved class C amplifier with common-mode feedback.
Some examples of conventional circuits are: U.S. Pat. No. 5,721,500; and U.S. Patent Pre-Grant Publ. No. 2006/0082416.